If the actor's contract is up for renewal, then of course the company is under no obligation to take up their option.
However, I have read the word 'terminated' in the media which suggests that he was under contract, and Granada have dismissed him.
I am quite sure that there is more to the story than is apparent from AOG's question - were it simply the word of one individual that would quite correctly be seen as unfair.
However, Granada are not stupid, and their lawyers will have advised them in advance that the termination will stick.
That coupled with an apparent absence of righteous anger and claims to be innocent, and looking for a day in court on behalf of the actor in question, he appears to be accepting his fate without question, which does infer that he regards fighting it as being against his best interests.